Process of treating paper



Patented May 11, 1937 7 UNITED STATES PATENT OFFICE PROCESS 0F :;:?:IING PAPI9R I v No Drawing. Application January 11, 1934,

Serial No. 706,289. Renewed September 24,

This invention relates to a process of treating paper to render it water repellent or water absorbent, as desired, with the added feature that in either case it will remain tough when wet, with increased strength, flexibility and softness and longer life, thereby creating more uses' for such paper products.

An object of the invention is to provide a process for treating paper stock so as to render Still another object is to provide a process for treating paper which will render it water repellent and tough when wet, and which is not injurious to foods, such as meats, wrapped therein.

These and other objects, as will hereinafter appear, are accomplished by this invention, which is fully described in this specification.

As an embodiment of my invention, I prepare a liquid which will now be described which is in the nature of a size through which is passed the paper stock to be treated. As a modification of this I may add this liquid to paper pulp in the beater and form paper from the pulp with this size mixed therein with substantially the same results. 1

I have found that a very satisfactory method mixing the following;

,. 1 Parts Cellulose pulp (by weight air dry) 30 -Caustic soda Water 300 Tung oil, castor oil, linseed oil, cotton seed oil, or soy bean oil The cellulose pulp may be of sulphite or sulphate wood pulp, or other vegetable pulp. The above ingredients are thoroughly mixed by stirring, the whole heating up due to chemical reactions which take place. After cooling to F. or less, thirty parts of carbon bisulphide is thoroughly mixed with the above and allowed to stand from forty-five minutes to three hours, or until the cellulose fibers substantially disappear. This is determined by passing some of the mixture through a sieve or cloth having a mesh of twenty-seven hundred parts is then mixed with the pulp forming a complete viscose.

If sheets of unsized or slack-sized paper are passed through this size and the paper is then passed through squeezing rolls and dried in any manner well known in the art, the paper so treated will be water repellent and will maintain' a large proportion of its toughness even after considerable amounts of moisture are absorbed. Such a paper is highly desirable for use as a wrapping paper, for paper bags, and the like. The water repellent feature may be emphasized by passing the paper so treated through an alum solution or by adding alum to the above size before the paper is passed through it.

For providing a paper for wrapping meats and foods of all kinds, I add to the base-emulsion ninety parts of soy bean oil, as it has no poisonous qualities as in the case of tung oil. Linseed oil may be used for this purpose, but is more costly than soy bean oil.

For moth proof bags and the like, I add to the base emulsion ninety parts of cedar wood oil. If this paper'is to be made water repellent, I add instead forty-five parts each of tung and cedar wood oils.

The addition of the carbon bisulphide to the fiber pulp causes the two to react, forming a xanthate, which toughens the paper treated but does not waterproof it. The oil renders it water repellent.

For making towels, however, I add to the base emulsion ninety' parts of sulphonated castor oil, and I preferably add five parts of pine oil to give the paper towels a pleasant odor. Sulphide or sulphate paper towel stock or the like is then passed through this size and is dried as before described.

A paper towel thus treated absorbs water much more quickly than ordinary sulphide and sulphate papers commonly used for towels, and when wet shows greatly increased toughness and tensile strength over that of untreated sulphide and sulphate towel paper when wet. It does not tear easily, and does not roll into balls or shed lint on the face and hands of the user, or disintegrate in any way even if the towel is covered with soap. If desired, this towel may be washed, dried and used again several times.

Another modification of the invention comprises mixing the oil with the carbon bisulphide. This has the advantage of preventing the oil from separating out and of making a single packis added at the point where the carbon bisulphide was added in the process first described.

It is necessary that the temperature of the viscose size be kept low in order to prevent the 5 formation therein of regenerated cellulose which is a solid whose deposition on the surface of the paper treated gives the paper the desired qualities. The temperature of the bath of viscose size should be below 70 F. ,The lower its temperature, the longer it can be run without requiring renewal.

The proportions of the ingredients may be varied somewhat. The proportions of pulp and caustic soda are such as to cause the pulp to be digested. Less oil may be used with decreasing effectiveness as a water repellent, but I have found the proportions as given to be very satis: factory,

The water absorbent paper may have liquid soap added to it while wet and then dried. This when again wet may be used as a wash cloth with soap contained threin,

While I have shown and described but a few embodiments of my invention, it is capable of many modifications. Changes, therefore, in the process steps may be made which do not depart from the spirit and scope of the invention as disclosed in the appended claims.

I claim:

l. The method of treating paper to render it water repellent comprising thoroughly mixing together thirty parts by weight of a cellulose pulp paper stock, forty-five parts caustic soda, three hundred parts water and ninety parts of a vegetable oil selected from the group consisting of drying, semi-drying and non-drying oils, cooling and thoroughly mixing thirty parts of carbon bisulphide with the other mixture, letting stand until fibers of paper pulp disappear, adding twenty-seven hundred partsof water, thoroughly mixing, and coating therewith paper to be treated.

2. The method of treating paper to renderit water repellent comprising thoroughly mixing together thirty parts by weight of a cellulose pulp paper stock, forty-five parts caustic soda, three hundred parts water and ninety parts of tung oil, cooling and thoroughly mixing thirty parts of carbon bisulphide with the above mixture, letting stand until fibers of paper pulp disappear, adding twenty-seven hundred parts of water, thoroughly mixing, and coating therewith paper to be treated.

3. The method of treating paper to render it water repellent comprising thoroughly mixing together thirty parts by weight of a cellulose pulp paper stock, forty-five parts caustic soda, three hundred parts water and ninety parts of soy bean oil, cooling and thoroughly mixing thirty parts of carbon bisulphide with the above mixture, letting stand until fibers of paper pulp disappear, adding twenty-seven hundred parts of water, thoroughly mixing, and coating therewith paper to be treated.

4. The method of treating paper to render it water repellent comprising thoroughly mixing together thirty parts by weight of a cellulose pulp paper stock, forty-five parts caustic soda, three hundred parts water .and ninety parts of a vegetable oil selected from the group consisting of drying, semi-drying and non-drying oils, cooling and thoroughly mixing thirty parts of carbon bisulphide, letting stand until all fibers of paper pulp disappear, adding suflicient water forming a complete viscose and coating therewith paper to be treated.

5. The method of making a treating compound to render paper water repellent comprising mixing together thirty parts by weight of cellulose pulp paper stock, forty-five parts caustic soda,

three hundred parts water and-ninety parts of a vegetable oil selected from the group consisting of drying, semi-drying and non-drying oils, cooling and mixing therewith thirty parts carbon bisulphide, letting stand until fibers of pulp disappear, and adding a sufiicient quantity of water forming a complete viscose.

6. A paper product coated with a water repellent viscose composition formed by thoroughly mixing together thirty parts by weight of cellulose paper stock, forty-five parts caustic soda, three hundred parts of water and ninety parts of a vegetable oil selected from the group consisting of drying, semi-drying and non-drying oils, and to which has been added after cooling thirty parts of carbon bisulphide, and twenty-seven hundred parts of water.

'7. A paper product coated with a water repellent viscose composition formed by thoroughly mixing together thirty parts by weight of cellulose paper stock, forty-five parts caustic soda, three hundred parts of water and ninety parts of a vegetable oil selected from the group consist ing of drying, semi-drying and non-drying oils, and to which has been added after cooling thirty parts of carbon bisulphide and a sufiicient quantity of water to form a complete viscose.

THOMAS HANS. 

